This invention relates to a fuel supply system for an engine, and more particularly to an improved fuel supply system for an engine having multiple charge formers.
In many applications for internal combustion engines, the engine is provided with a plurality of charge formers. With such an arrangement, it is desirable to ensure that fuel is delivered uniformly and equally to all of the charge formers by the fuel supply system. Although this is generally not a problem, with certain types of applications for internal combustion engines, it can become a problem.
For example, with some applications for internal combustion engines, the charge formers are disposed so that they are positioned vertically above each other. This is typical, for example, in outboard motor practice. In outboard motors, the engine is disposed so that its output shaft rotates about a vertically extending axis. As a result, the individual cylinders extend generally horizontally and are disposed in vertically spaced relationship. The carburetors or other charge formers, therefore, adopt a similar attitude and disposition.
The problem with vertical positioning of the charge formers is that in the fuel delivery system, which frequently includes a single conduit or manifold that extends from the fuel pump to all charge formers, the conduit may be configured in such a way that it forms areas where fuel or vapor may become trapped. This vapor trappage is a problem due to the possibility of heat causing vaporization of the fuel in the fuel manifold. If a fuel vapor pocket forms, then the charge formers downstream of the vapor pocket will not receive fuel, and obvious problems can result.
In order to attempt to alleviate these problems, it has been proposed so as to provide the fuel pump at a lower location than the charge formers. In order to further reduce the likelihood of vapor blockage, the fuel pump may be provided with a plurality of fuel outlets and conduits that feed respective carburetors of the system. With this type of arrangement, however, the fuel pump is normally positioned below the lowest carburetor, and this results in a restriction in the ability of the fuel pump to deliver fuel due to the relatively high head between the fuel pump and the highest carburetor. Also vapor venting is not assured.
It is, therefore, a principal object of this invention to provide an improved fuel supply system for an engine.
It is a further object of this invention to provide an improved fuel supply system for an engine having vertically spaced charge formers.
It is a still further object of this invention to provide an improved fuel supply system for an engine having vertically spaced charge formers and wherein the system will ensure against vapor blockage and further will permit shorter fuel supply lines.